In the agricultural industry there is a need to control plant pathogens that would otherwise destroy crops and reduce yields. Farmers have traditionally employed a variety of methodologies to control these pests, one of which has been the use of compounds with antimicrobial activity, called fungicides, to protect the plants and prevent crop damage. There are many types of plant diseases, and foreign microorganisms can be introduced into new areas causing disease outbreaks. Current fungicides have traditionally been chemically synthesized compounds that have limited spectrum of activity and often require repeated usage creating a cause for environmental concern. These concerns include contamination of foodstuffs, soil, surface and ground water and their impact on native microbial and insect populations. In addition, pathogens have been able to develop resistance to conventional fungicides, and as a result the industry is consistently searching for new chemical compounds with new modes of action to combat disease resistance.
Ilicicolin H is one of several natural secondary metabolites made by imperfect fungi. These metabolites generally act as protectants for the fungus. Ilicicolin H is produced by strains of Cylindrocladium iliciola (Hayakawa et al., “Ilicicolins, antibiotics from Cylindrocladium ilicicola”, Journal of Antibiotics 1971, 24, 653-4) and Fusarium sp. (Shao et al., “Metabolites of endophytic fungus Fusarium from Spartina alterniflora”, Zhongguo Tianran Yaowu 2007, 5, 108-111), and Gliocladium roseum (Junker et al., “Scale-Up Studies on a Defined Medium Process for Pilot Plant Production of Ilicicolin by Gliocladium roseum,” Biotechnology Progress 2001, 17, 278-286).
Ilicicolin H is an antibiotic that was first identified to have activity against the human pathogen Candida albicans and was investigated for use in the treatment of complications to HIV infection in humans (Guetierrez-Cirlos et al., “Inhibition of the Yeast Cytochrome bcl Complex by Ilicicolin H, a Novel Inhibitor That Acts at the Qn Site of the bclComplex,” Journal of Biological Chemistry 2004, 279, 8708-8714). Ilicicolin H whose structure is shown below is a 5-(4-hydroxyphenyl)-2-pyridone with a bicyclic decalin system. The compound inhibits the mitochondrial respiration of certain fungi by inhibiting the cytochrome bcl complex. Ilicicolin H has low cyctotoxity (HeLa cells, ED50=2 ug/ml) and low acute toxicity in mice (Hayakawa et al., “Ilicicolins, antibiotics from Cylindrocladium ilicicola,” Journal of Antibiotics 1971, 24, 653-4). However, Ilicicolin H has not previously been shown to be active against plant pathogenic fungi.

It has now been found that Ilicicolin H is useful as an agricultural fungicide to treat, prevent, or control fungal infections in agricultural products, such as plants and seeds.
One aspect of the present invention is concerned with agricultural compositions of Ilicicolin H comprising an effective amount of the antifungal compound and an agriculturally acceptable carrier. Such compositions may additionally comprise one or more excipients selected from the group consisting of (a) one or more diluents, (b) one or more binders or binding agents, (c) one or more dispersing agents, (d) one or more emulsifying agents, (e) one or more surfactants or wetting agents, (f) one or more sticking agents, (g) one or more thickening agents, and (h) a pH adjuster. In one embodiment the surfactant is an anionic surfactant. In a second embodiment the surfactant is a non-ionic surfactant.
Ilicicolin H and agricultural compositions of Ilicicolin H of the present invention may also be used in combination with one or more other agents useful to treat, prevent, or control agricultural pests in the field. In such combinations the compositions of the present invention and other active agents may be administered separately or in conjunction. In addition, the administration of one element may be prior to, concurrent to, or subsequent to the administration of the other agent(s).
Examples of other active ingredients that may be administered in combination with compositions of the present invention, and either administered separately or in the same agricultural composition, include, but are not limited to:
(1) antifungal agents, such as azoxystrobin and myclobutanil;
(2) plant growth regulators, such as dikegulac-sodium and trinexapac-ethyl;
(3) herbicides, such as prodiamine and glyphosate;
(4) insecticides, such as bifenthrin and malathion; and
(5) acaricides, such as avermectin and kelthane.
The agricultural compositions of the present invention may contain about 0.1 to 95 percent by weight Ilicicolin H.
It is another aspect of the present invention to provide methods of treating, controlling, or preventing fungal infections on an agricultural product comprising applying to the agricultural product or plant the present agricultural compositions of Ilicicolin H. The compositions of the present invention may be applied using a variety of methodologies, including soil drench, seed treatment, granular and foliar spray. With regard to the treatment of seeds, the compositions may alternatively be applied directly to the seed before planting of the seed or applied to the locus or soil in which the seeds are sown prior to the planting of the seed.
In such methods of the present invention the concentration of Ilicicolin H to be applied to the agricultural product is about 0.001 to 1 percent by weight. In a class of this method the concentration of Ilicicolin H to be applied to the agricultural product is about 0.001 to 0.01 percent by weight.
Another aspect of the present invention relates to the total amount of Ilicicolin H to be applied per area of the field. In one class of this aspect about 2 to about 1000 grams of Ilicicolin H are to be applied per acre. In a subclass of this class about 5 to 500 grams of Ilicicolin H are to be applied per acre. In a second class of this aspect about 0.025 kilograms to about 5 kilograms of Ilicicolin H are to be applied per hectare. In a subclass of this second class about 0.05 kilograms to about 1 kilogram of Ilicicolin H are to be applied per hectare.
Another aspect of the present invention relates to the use of Ilicicolin H and the compositions of the present invention to treat, control, or prevent fungal infections on an agricultural product.
It is another aspect of the present invention to provide for the use of Ilicicolin H in the manufacture of a composition for use in treating, controlling, or preventing a fungal infection on an agricultural product.
The present invention also relates to a food, feed, or agricultural product treated with a composition of the present invention.
The present invention also relates to a process for the treatment of an agricultural product which comprises applying a composition of the present invention to such agricultural product or plant.
The present invention also relates to the use of a fermentation broth derived from strains of Cylindrocladium ilicicola and Gliocladium roseum as a live cell or cell suspension to treat, control, or prevent a fungal infection on an agricultural product. Such fermentation broths contain the antifungal agent Ilicicolin H which need not be isolated, purified, and re-formulated for use as an agricultural fungicide.
These and other aspects will become readily apparent from the detailed description of the invention which follows.